where \(h\)  denotes the dimensionless Hubble parameter (\(h=0.6766\)  [1]}), \(M_{\rm Pl}=G^{-1/2}\)  is the Planck mass, \(\gamma \simeq 0.2\)  denotes a numerical factor that depends on the details of the gravitational collapse [2]}, \(g_\ast \)  denotes the relativistic effective degrees of freedom for the radiation energy density, and \(M_{\rm PBH}\)  is the initial PBH mass.
